Variable speed transmission mechanism



Jan.17,1939. MPALM-GREN 2, 44, 7

VARIABLE SPEE D TRANSMISSION MECHANISM Filed Feb. 27, 1936 4Sheets-Sheet 1 BY I Nils Arvid Palmgren 1N VENTOR.

*4} ATTORNEY.

Jan. 17, 1939. N. A. PALMGREN vAriIABLE SPEED TRANSMISSION MECHANISMFiled Feb. 27, 1936 4 Sheets-Sheet 2 I 'INVENTOR. Nils Arvid Palmgren N.A. PALMGREN VARIABLE SPEED TRANSMISSION MECHANISM Jan. 17", 1939.

Filed Feb. 27, 19 36 4 Sheets-Sheet 3 INVENTOR. Nils Arvid Palmgren BY%TORNEY.

N. A. PALMGRIVEN r 4 70 VARIABLE SPEED TRAN SMI S S ION MECHANI SM FiledFeb 27, 1936 4 Sheets-Sheet4 180 1 swig a 5b INVENTOR. Nils ArvidFalmgren %ATTORNEY.

Patented Jan. 17, 1939- v PATENT OFFICE 2,144,270 VARIABLE srnenmansmsslon MECHANISM .Nils Arvld Palmgren, Goteborg, Sweden ApplicationFebruary 27,1936, Serial No. 66,007

lz clatm s. (01. 14-260) This invention relates to variable speed power.transmission mechanisms of the planetary gear type, and its chiefobject, briefly stated, is toprovide readily operable means for varyingthe ratio 5' of the velocities of the driving and drivenparts and of thetorque input and output in a great, number of steps with a minimum ofoperating power and without disconnecting the said parts from the powersource or diminishing the input the driver; greater safety in driving;high 'efli-,

ciency; damage to the mechanism virtually imj possible in shifting;ability to shift at high car brake; rapidity of shifting no necessity todisengage main clutch when shifting; no necessity to close the enginethrottle when shifting; automatic drive ratio change only to prevent theengine from stalling at low car speeds.

Economically my invention has still greater advantages. The'car runs ofnecessity with the engine throttle fully open when driving in any onebut the top drive ratio, as soon as the engine antifrictiontype,disposed centrally inthe front torque. I runs at a velocity,- higherthanfits lowest con- 9 A special object of my invention is to providevenient velocity a transmission mechanism by which it is possible Onaccount of this feature of the transmission for the operator to keep thetransmission ratio mechanism the eificiency of the engine is always atall times at avalue at which the input torque kept at its highestpossible value and the fuel is a maximum and thereby to increase theeconeconomy of the engine is considerably increased. 5 omy of the powerplant. At the same time any of the transmission drive A further objectof the invention is to provide ratios is readily attainable merely bydepressing means for keeping the speed of the primary shaft theaccelerator pedal. It is not possible to partly as low as theoreticallypossible at any desired close the engine throttle, without the transmis-Output torque and speed. sion. mechanism running in top drive ratio;-above 20 A further object is to provide a transmission a certain carspeed, whereby the engine is spared mechanism'which is operatedexclusively by the as much as possiblei C will of the operator, as longas the motorruris Referring to the accompanying drawings, in at a speedabove its minimum and to incorporate which the preferred embodiment isshown:

means for automatically preventing the motor Figure 1 is an elevationview of a mechanism, 25

from stalling. partly in section, made in accordance with my A furtherobject is to provide means for obtaininven flfl, ing a powerful motorbraking effect at negative F gu e 2 is a section On the e of Figure 1output torque. 4 Figure 3 is a section onthe line 3-3 of Figure 1,

a0 A still further object. is to incorporate power- Figure 4 is asectional de view o a o e way operated means for the changing of gearratios c 7 and thereby minimizing the operating efforts on Figure 5 is aside view of certain external'parts the part of the operator. of themechanism as arranged in a car, i

Still another object is to provide a semi-con Figure 6 is a development,on a plane surface, tinuous transmission mechanism by incorporating ofthe distributor sleeve and its Ope a relatively great number oftransmission ratios. Figure 'l is a m. ill tratin the r la io A specialobject of the invention is to provide between car speeds, enginevelocities and trans means for combining the operating members of s o de ratios, and l l the transmission mechanism and the power source Fi e 8is a fragmentary sectional view illus- 4o'in order to simplifyoperation. I trating a modification within the scope of the 40 It isbelieved that the invention will find its invention. chief utility inthe' automotive field, and accord- -With reference to the drawings; thereference ly in the subjoined description it will be excharacter 3indicates the front part of a transplained and discussed with referenceto that use, mission housing, 4 the middle part and 5 the rear 7 withthe understanding however, that itis not partof. said housing. Part aand pa t 4 are ev limited thereto, r movably secured to each other bybolts 6. Parts In its preferred form, herein'desc'ribed, my in- 4 and 5are removably secured to each other by: vention possesses a number ofimportant advanbolts 1. An oil container, in, 4a, is provided at tages,such as case and simplicity of operation, the bottom of housing parts 3and l. The hous- .Jwth practically no skill required on the part of ingis equipped with a'bearing 8, shown as of end ofthe housing part 3. Thebearing Bare-7.. V.

celves a hollow shaft 8; provided with a. nondetachable dog clutch IIIat itsfront end and e drive ratio at whichthe engine would'act as a wormgear. at its rear end within the' housing 58' i I. The driving shaft l iis Journaled within the hollow shaft 5 and provided with splines ii atits front end to receive the hub of a conventional main friction clutchdisc, not shown. The mid- 5 die part 4 of the housing supports a'bearingl4, receiving an intermediate shaft l5. The rear part 5 of the housingsupports two bearings, l5 and I1, receiving the driven shaft l8. Thedrivingshaft Ii comprises a front part l lid, and a rearpart lib, fittedwithin a bore IS in the rear, end of shaft part Iia. The' shaft part libis Journaled in a bore in the front end of the intermediate shaft andthe rear end of said intermediate shaft I5 is Journaled in a bore l5 in,the. front end of the driven shaft It. The

aligned coincidental axes of driving, intermediate and driven shaftsconstitute the main axis of the transmission.

The shaft part lib is provided with four key-- .0 ways, il, il, ii andii respectively, extending from near the front end to near the rear endof.

the shaft part lib. -The ends of these four key-.

of the shaft ii affords access to the fluid-pressure channel il in shaftIi. Similar openings, shown no in Figure 2 in dotted lines, affordaccess to the remaining shaft channels il, ii and ii, all four openingsbeing situated in the same radial plane of the shaft Ii. Opening in theenlarged part it of the shaft ii is provided for optionally put- 3.1ting the shaft channel il in communication with the interior of thetransmision housing 3, and similar openings for the remaining shaft'channels, all situated in one radial plane.

and snugly fltted to the same is a distributor sleeve i1, acting as avalve member and is mounted axially movable in relation to the shaft iiand rotating therewith and provided with openings ii for optionallycommunicating with the shaft channels and openings ii for puttingtheshaft channels into communication with the interior of thetransmission housing when the sleeve 21 c closes the openings 24 in theshaft Ii. In abore .ill in the shaft li, shown in Figure 1 and Figure 5g2. is placed a spring plunger, consisting of a coil spring I! and twoballs Ii, snapping in grooves 85 in the bore of the distributor. sleevei1. A

number'of grooves 83, shown in dotted lines in Figured are cut in thebore of said sleeve, in two; 5.5 diametrically opposed rows, andjaxiailyspaced for determining the different axial positions of.

the distributor sleeve 21, the axial distance between two adjacentgrooves It being equal to the axial distance between the openings i4mutually no as well as the openings il mutually.

Surrounding the shaft Ii and the distributor sleeve i1 is a housing.part '54 mugly fitting the outside vof said dist'ributonsleeve. Afluid-pressure channel 55 in said housing 54, communicat- 1:.',/ ingwith the pressure side of a fluid pump 36 of the Imo-screw type, builtinto the housing 84. A

circumferential opening 31 is arranged in the bore of the housing but34' in the same radial.

plane as the openings 24 in the shaft li, through 70 whichfluid-pressure may be transmitted from the pump It .to the differentfluid pressure channels and working chambers of the mechanism.

# l'heiiuld-p gsflure generated by the pump 36 is A limited by means of'a conventional pressure limitingvalve It. The pumpscrew Ito'is drivenSurrounding the enlarged part it of the shaft from 'the hollow shaft 9by the worm gear Ii. Said shaft 5 in its turn is driven directly by theengine 39 through the non-detachable dog clutch l0, whereas the drivingshaft Ii is driven by said engine through a conventional detachable mainfriction clutch, not shown, fitting the splined front end ii of theshaft l2.

An operating bearing 40 of the antifriction type is mounted. on part 21aof the distributor sleeve member 21, the stationary outer race of whichbearing may be pushed axially at will in a direction'toward the rear ofthe mechanism by means of a fork 4|, fitted to a transverse shaft 42,

'rockably supported by the transmission housing the pedal, whereas aspring b moves the lever 45a to open the throttle, when the pedal 43 isdepressed.

Keyed to the shaft ii there is a ring gear member "of a first planetarygear unit, said first planetary gear unit being constituted by the sungear member 48, the planetary pinion member 45 and the ring gear member41. ring gear member 41 'cooperateswitha plurality of annular frictionclutch discs a, surrounding said ring gear member and axially movablewithin limits in relation thereto and provided with lugs 50b, projectinginto longitudinal grooves 52, cut in the ring gear member 41.Surrounding the ring gear member 41 andaxially movable in relationthereto there is further'an annular clutch actuating member 53, having agreater bore diameter at the end. 54 facing the clutch The discs 50a anda smaller bore diameter at the opposite end 55-, said bores looselyfitting corresponding outside diameters of the ring gear mem- 1 ber 41.Said ring gear member and the annular clutch actuating member 53 thusenclose an annula'r fluid-pressure working chamber 56, eflecvtivelysealed by piston ring-packings 51 and communicating only with the shaftfluid-pressure channel 20 through channel '58 in the ring gear member41.

Between the flange 59, fixed to the ring gear member 41 and the annularclutch actuating member 53, a set of helical clutch springs 6|] isinterposed, urging the clutch actuating member 53 in a direction towardthe clutch discs to en-' gage the clutch. The clutch actuating member 53may be backed off leftwardly in Figure 1 away from the clutch discs 50aagainst the tension of the springs by the introduction of fluid pressurein said fluid-pressure working chamber 55, in which event the clutch isdisengaged. The sun gear member 48 is provided with an extension 6!carrying a plurality of annular friction clutch discs 5la axiallymovable in relation to said extension and prevented from rotating inrelation thereto by means of lugs 5Ib and corresponding longitudinalgrooves 53 in the bore'of the extension 6|. These last mentioned clutchdiscs5l a are interposed between respective clutch discs 50a to completethe multiple disc friction clutch 6i, optionally connecting the ringgear member 41 and the sun gear member 48 of said first planetary gearunit. The sun gear memi i 2,144,270 ber 48 is journaled on the tubularpart of clutch part 68b of the sun gear member 88 of a second planetarygear unit, described below.

The second planetary gear unit comprises a ring gear member 54, aplanetary pinion member 65 and a sun gear member 86. The planetarypinion members 49 and 65 of the first and secnd planetary gear unitsrespectively are connected in that the planetary pinion 49 is journaledon the same shaft 61 as is the planetary pinion 65. The planetary pinioncarrier is common to both said members 49 and 85 and is journaled on thesun gear member 48 on one side and on the ring gear member 64 on theother side. The sun gear member 48 of the first planetary gear unitreceives the outer ring 68a of a oneway clutch 69 of the roller type,the inner ring 10 of which is keyed to the fixed housing part 1|,interposed betweenhousing parts 3 and 4 and held by the bolts 8. Thisone way clutch B9 is shown in sectional side view in Figure 4.Theraceway 88b of the outer ring 68a is purely cylindrical, whereas theouter surface of the inner ring 1|] is provided with spiral parts 12 andaxial grooves 13 interrupting said spiral parts. A roller 14 isintroduced between the outer race- .way 68b and each one of the spiralsurface parts with one side of the respective groove 13. clockwiserotation in Figure 4 of the outer ring 12 of the inner ring 1|], therollers being corre'ctly spaced apart by a retainer 15. The retainer 15and the set of rollers 14 are shown in Figure 4 in the free-wheelingposition, determined by the lugs 18 of retainer 15, contacting A 68aresults in a rotation of the set of rollers 14 and the retainer 15'until the rollers interfere.

with the spiral surfaces 12 of the inner ring and the raceway 88b of theouter ring 88a and thereby lock the clutch. The one way clutch 69prevents the sun gear member 48 from rotating in the reverse direction.

The ring gear member 64 of the second planetarygear unit is splinedtothe tubular shaft ,11, in its turn splined to the sungear member 18of'the third planetary gear'unit, constitutedby the sun gear member 18,the planetary pinion member 19 and the ring gear member 80. The sun gearmember 88' of the second planetary gear unit is built up by the gearwheel 8611 and the,

clutch part la-splined .to each other. The clutch part 66b is journaledon thetubular shaft 11 and carries a multiple disc friction clutch 82,similar to the clutch 62, and optionally connecting the v sun gearmember 88 and the fixed housing part 1|. In this clutch thefluid-pressure working chamber 83 communicates with the shaft channel 2|through a channel 84 in the clutch part l 6612 and openings 8| in thetubular shaft 11.

The clutch part 88b is connected to the sun gear member 18 of the thirdplanetary gear unit by means of vaone wayclutch 840,01 the same designas shown ir'nFigure 4. This one way clutch 84a prevents the sun gearmember 86 from rotating faster than the ring gear member 64.

The planetary pinion member 19 of the third planetary gear unitislsplined to the intermediate shaft I5. The ring gear member 89 isjournaled on said shaft l5. A multiple disc friction clutch .85 of thedesign described above,,is attached to said ring gear member 80optionally .connecting said member 80 and the sun gear member 18. Thefluid-pressure working chamber 86 of said clutch 85 communicates withthe shaft channel 2| through channels 81 in the ring gear member 88 andopenings 88 in the intermediate shaft l5. The ring gear member 8|] isconnected to the fixed housing part 89, fastened to the housing part 4by the bolts 89a, by the one way clutch 90 of the type described above.This one way clutch 9|) prevents the ring gear member 8|! from rotatingin the reverse direction. Splined to the intermediate shaft l5 there isa member 92. This dog clutch sleeve 94, which is operatively associated.with a hand lever, not shown; is shown ,in Figure 1 in a neutralposition. Moving the sleeve 94 to the left of Figure l'to engage thefixed housing part 4, the planetary pinion member 92 is immobilized andthe ring gear member 93 is rotatable in the reverse direction. Movingthe sleeve 94 to the right in Figure 1-to engage the ring gear member93, the said fourth planetary gear is rotatable as a rigid unit in theforward direction. The ring gear member 93 is splined to the drivenshaft |8.

The planetary pinions 49, 65, 19a and 92a of the respective planetarygear units are journaled on shafts 61, 19b and 92b, a plurality ofcylindrical bearing rollers 190 being interposed berespectively,corresponding to the "openings 24;

and 25 respectively of the shaft l2. Onecircumferential row. of-openingsin each of the mentioned two series and two grooves 33, diametricallyopposed, correspond to each axial position of the distributor sleeve 2|.

The shaft channel 23 only collects leaking oil and conveys said oil tothe gearing for lubricatihg purpose. 7 1

In sleeve position a, the openings 28a give access for the pressurefluid to the shaft channels 28, 2| and 22 and the working chambers 55,83 and 86 of the friction clutches 82, 82 and 85 respectively and fluidpressure disengage said clutches; The sun gear unit 48 is therefore'pre+ vented from rotating in reverse direction by the one way clutch 89I attached thereto, and the first planetary gear unit is working. Thering gear member 80 is prevented from rotating in reverse direction bythe one way clutch 98 and therefore the third planetary gear unit iswork- 'ing. The sun gear member 88 is prevented from running faster inthe forward direction than the sun gear member 9| of a fourth planetarygear unit, the planetary pinion member 92 of which .carries a dog clutchsleeve 94 splined tosaid ring gear member 84 by the one way clutch 84,and the second planetary gear therefore,

rotates as a rigid unit. In'the described case the gearing runs infirstgor lowest drive ratio.

The expression drive ratio" as used here always means the outputvelocity, divided by the input velocity.- 1 I In distributor sleeveposition b, the openings 28b continue to afford fluid-pressure access tothe shaft channels 21 and 22, whereas the open ing 2% opens theshaftchannel 28 and permits the fluid in said channel and in the workingchamber 58 of the clutch 82-to escape into the transmission housing. Inthis case 'the clutch whereas the shaft channels and 2| are opened bythe slots 290. In this case therclutch 921s engaged and the secondplanetary gear starts to work, giving third drive ratio.

In sleeve position d, the openings 29d introduce fluid-pressure inchannels 20 and 2|, the

clutches 62 and 82 are disengaged, whereas open-' ing 29d causes clutch95 to be engaged. The first planetary gear unit worksand the second andthird planetary gears revolve as rigid units. This is fourth driveratio.

In sleeve position e, the opening 29c opens the shaft channel 20 and allthree planetary gears revolve as rigid units. This is fifth drive ratio.And finally in sleeve positon I, all the shaft channels 20, 2| and 22are opened by the .slots 29!, causing the first and third planetarygears to revolve as rigid unit's, whereas the second planetary gear unitworks. This is sixth or top drive ratio. r,

The section through the distributor sleeve member 21 in Figure 1 showssaid sleeve member in position e, described above, corresponding tofifth drive ratio or direct'drive.

A set of centrifugal weights 95 are pivotally mounted on transverseaxles 96a at the front side of flange 59 and are capable of rocking within limits in an axial plane of the gearing main axis. Centrifugal weightreturn coil springs '96 cooperate vwith the centrifugal weights 95 andthe flange 59. The centrifugal force at rotation of the driving shaft l2tends to displace the centrifugal weight outwardly, whereas the returnsprings 96 counteract this'tendency. The cantrifugal weight 96 isprovided with a distributor .sleeve operating arm 91, cooperating withthe flange 98 on the distributor sleeve member part 21a and capable ofmoving the distributor sleeve axially to the right in Figure 1 againsttension of the distributor sleeve return coil spring 99, inter- Posedbetween the distributor sleeve member 21 and the ring gear member 41. Athigh angular velocities of the driving shaft [2, the centrifugal weightsare thrown outwardly, extending the springs 96 and releasing thedistributor sleeve member 21. At the lowest convenient velocity of thedriving shaft l2, say for instance 700 revolutions, per minute the axialforce exerted by the springs 96 on the distributor sleeve 21 through theintermediary of the arm 91 and flange 99, is equal. to the sum of theaxial forces on said member 21 exerted by the centrifugal force onweights 96, the return spring. 99 and the resistance force of the springplunger 92. If the velocity of the shaft l2 diminishes to come belowthis limit, the. distributor sleeve is moved one step to the rear, thatis to.the right in Figure 1, causing the transmission. mechanism tochange its drive ratio one step to a lower ratio. At about constant carspeed, the engine velocity is therefore increased correspondlngly, butthe'forces acting on the distributor sleeve 21 .are so chosen, that thenew drive ratio rmnains in spite of the increased centrifugal for Toalter the drive ratio back to its higher 'valu ,it is required that thesum of the centrifugal weight force and the distributor sleeve returnspring force on the sleeve is equal to the sum of the centrifugal weightreturn spring force and the spring plunger resistance force'on saidsleeve. Thiscanbemade tooccuratanlmlularvelocity of the driving shaftl2, which is higher than the lowest convenient velocity of said shaft,multiplied by the step up ratio between two neighboring drive ratios ofthe transmission mechanism.

For this purpose the forces acting may be chosen in accordance with thefollowing example. The distributor sleeve return spring force is 6 lbs.the spring plunger resistance 2 lbs. in either direction, thecentrifugal force transmitted to the distributor sleeve 2 lbs. at 700 R.P. M. and 6 lbs. at 1200' R. P. M.,'and the centrifugal weight returnspring force transmitted to the distributor sleeve 10 lbs. To move thedistributor sleeve 21 to the right in Figure 1, the centrifugal weightreturn-spring force, 10 lbs. must be equal to the sum of the distributorsleeve return spring force, 6 lbs. thespring plunger resistance, 2 lbs.and the centrifugal force. .This will be thecase when the last mentionedforce is 2 lbs. that means at 700 R. P. M. To move the sleeve to theleft in Figure .1, the sum 'of the distributor sleeve return springforce, 6 lbs. and the centrifugal force must be equal to the sum of thecentrifugal weight returri spring force, 10 lbs. and the spring plungerresistance, 2 lbs. which is the case when the centrifugal force is 6lbs. that means at 1200 R. P. M. If now the two neighboring drive ratiosof the transmission mechanism are 1.0 and 1.43, for instance, thedriving shaft I2 is allowed to speed up from 700 R. P. M. to 1000 R. P.M. when drive ratio changes from 1.43 to 1.0 at constant car speed. Butthis velocity increase is not sufiicient as indicated above, to causethe. mechanism to immediately change back to 1.43. In this way theautomatic, centrifugally operated mechanism is stable.

To operate the distributor sleeve 21 at high engine velocities by theaid of the accelerator pedal 43, an axial force amounting to 8 lbs. is

Planetary pinion of the first and second units- 19 Sun gear of the firstand second'units 29 Ring gearof the first and second units 67 Planetarypinion of third and fourth unit 1'! Sun gear of third unit 37 Ring gearof third unit 71 Sun gear of fourth unit- Ring gear of fourth unit -L.59

Accordingly the forward drive ratios of the described gearing arc thefollowing. 0.24; 0.35; 0.50; 0.70; 1.00; 1.43 a and the reverse driveratios:

Assuming a back axle gear drive ratio of 13 to 51, or 0.255, thefollowing drive ratios of the en-. tire car transmission in forwarddrive are available, namely: I

0.061; 0.089; 0.127; 0.178; 0.255; 0.365 In accordancewith the describedfeatures of the mechanism, the relation between the car speed, enginevelocity and drive ratio of the en- .-tire car transmission is plottedin Figure '7, as-

sumins a maximum engine velocity of 3500 R. P. M. and a rolling radiusof the car wheels of 14 inches. The horizontal axis er the diagram in-.-to the rear of the sleeve position determined by dicatescar speed inmiles per hour, and the vertical axis drive ratio. The dotted vectorsindicate engine velocity in R. P.. M. The shaded area in the diagramindicates the practically possible drive ratio range as a function-ofthecar speed. At. for instance, 4 5 M. P. H. the engine runs at 1500 R.P. M. on the top drive ratio 04365,

the engine throttle being operated between idling and full loadpositions, according to the road resistance.

running uphill, it' maybe'necessary to increase the wheel. torque aboveits maximum obtainable To maintain the said car speed when by merelyopening the throttle. This is possible by depressing the acceleratorpedal beyond its full-throttle position to shift into fifth or even intofourth drive ratio. If it were attempted,

however, to shift into third Idrive ratio, the neces-' sary enginevelocity for propelling the car would notice available. Therefore ashifting into third drive ratio would result in free-wheeling until the"car speedfalls below 37 MVP. H. At 21 M. P. H.

the automatic centrifugaldevice starts actuating the transmissionmechanism to decrease the drive ratio and keep the engine velocity.above 700 R. P. M. independent of the throttle position. But at the sametime-any still lower drive ratio may bereadily obtained at will, bysufliclent depression of the accelerator pedal. Above acar speed of 21M. P. H. the engine throttle is fully opened when driving on any one buttop drive ratio, whereas below 21M. P- H. any throttle posi-' tion ispossible as long as the drive ratio determined by automatic device isworking. In con- 7 3B. Fluid pressureis then available.

1200 R. P. M'., thethird drive sequence the transmission permitscomfortable driving at all car speeds between about 3.5 and 105 (milesper hour, subject tothe limitations set by the available engine power.

The transmission mechanism operates as follows: The hand lever being putin neutral position', the dog clutch sleeve 94 is brought to its middleposition, shown in Figure 1. The planetary pinion member 92 is thenidling and no torque can be transmitted to the driven shaft.

I8. The engine having been started, the hollow shaft 9 is steadilyrotating and driving the pump By depression of the main friction clutchpedal the driving shaft I2 is disconnected from the engine,

and the dog clutch sleeve 94 may readily be moved rearwardly to engagethe ring gear mem ber 93. Now the driving shaft I2 is not rotat ing, andthe centrifugal weight return springs 96 force the distributor sleeve 21rearwardly, by the described means, to its extreme position,corresponding to position a, as described with refer-j ence to Figure 6,which gives the firstor low drive ratio. The main clutch pedal now being,raised, the driving shaft I2 is connected to the engine and the carstarts, the transmission mechanism running on first low drive ratiountil the engine velocity exceeds a predetermined value, say 1200 R.P.M.

At this point, the centrifugal force on weights 95 is great enough topermit the distributor sleeve 21 to be moved by spring 99 to position b,resulting in. a changeinto second drive ratio and a reductionofenginevelocity to 70 percent'of its former value.

The engine again speeding up to ratio is obtained,

and so on.

If however, the'accelerator pedal is depressed farther than to itsmiddle position, the fork 4| keeps the operating bearing 40 andconsequently the distributor sleeve 21 in any desired position tion.

. the centrifugal regulator device, thereby preventing the gearingv fromchanging to higher drive ratios and giving any acceleration desired,

. suits in a successive closing of the engine throttle.

Releasing the accelerator pedal entirely at high car speeds results in amoderate braking effect, as the transmission mechanism has nofreewheeling property on top drive ratio, no one of the one way clutchestransmitting torque on top drive. Coasting or braking the carto runbelowa predetermined speed, say 21 M. P. H., corresponding to 700 R. P. M. ofthe engine in the example taken above, the centrifugal; regulator causesthe mechanism to change to-a lower drive ratio until the minimum carspeed is reached,

when it is necessary to disengage the main clutch in the usual way toprevent the engine from stalling. v a

For reverse driving, the dog clutch sleeve 94 is brought to engage thehousing part 4. The planetary pinion member 92 is then prevented fromrotating as a whole; only the',planetary' pinions 92a therein are freeto rotate about their respective axles 9%, driving the ring gear--member93 and the driven shaft H8 in a reverse direc- On reverse gear also sixdifierent drive ratios are available. 1

Starting the engine by the aid of the inertia of the running car ispossible, because the hollow shaft 9 and therefore the pump 36 isstationary when the engine is stationary. All the fiuid-pressureactuated clutches of the mechanism are therefore engaged by theirrespective clutch springs and the device is in top drive ratio. The topdrive ratio is suitablefor the purpose, as it has no free-wheelingcapacity and applies a high torque to the engine.

It will be noted that the transmission mechanism in its preferred form,described above, is not to beregarded as an automatic transmission,since the gear changes as a rule are fully dependent on the driver'swill. But the transmission automatically prevents the engine fromstalling at low car speeds andkeeps the engine velocity as low aspossible at low, but increasing car speeds. This automatic action cannotpossibly be considered as confusing to the driver in any way. l

It may be desired to incorporate means in the transmission mechanism"for making a more powerful motor braking effect possible than thatFigure 8 shows such tionclutch discs IOI, held by grooves I02 in memberI05. I nterposed between such clutch discs IOI there are correspondingclutch discs I03 resting in the housing part 4 andheid by grooves I04therein. The discs of the clutch I00.

-may be pressed together by part I05. abutting against the axiallymovable clutch operating part I01, belonging to the friction clutch 85,shown .1 'in l 'igure 1. It now the distributor sleeve 21 is put inposition 0 to give third drive ratio, iluid.-'

pressure is introduced in the working chamber 06, the clutch II isdisengaged and the clutch I00 is engaged. Therefore the connectionbetween the driving shaft I2 and the intermediate shaft I5 is positiveand torque may be transmitted from the wheels to the motor, giving thedesired braking effect.

It is to be understood that the invention is not limited to theconstruction herein specifically de scribed, but can be embodied inother forms without departure from its spirit.

Having thus described my invention, I claim and desire to secure byLetters Patent:

1. A transmission mechanism comprising driving and driven elements, andat least three coaxial planetary gear units operatively associatedrespectively with said elements and with each other and jointlyconstituting a variable speed gearing connecting said elements, thedriving ele-,

ment being connected to the ring gear member of the first adjacentgearunit, the planetary pinion member of said first gear unit beingconnected to the planetarypinion member of the second gear unit, thering gear member of said second unit being connected to the sun gearmember of the third gear unit and the planetary pinion member of saidthird gear unit being connected to thedriven element.

2. A transmission mechanism comprising driving and driven elements, andat least three coaxial planetary gear units operatively associatedrespectively with said elements and with each 1 other and jointlyconstituting a variable speed gearing connecting said elements, thedriving element being connected to the ring gear member of the firstadjacent gear unit, the planetary pinion member of said first gear unitbeing connected to the planetary pinion member of the second gear unit,the ring gear member of said second unit being connected to the sun gearmember of the third gear unit and the planetary pinion member of saidthird gear unit being connected to the driven element, a friction clutchfor optionally connecting the sun gear member and the ring gear memberof the first gear unit,

a one way clutch operative on the sun gear member of said first gearunit and a fixed memher, a friction clutch for optionally arresting thesun gear member of the second-gear unit, a one way clutch operative onthe sun gear member of said second gear unit and the sun gear member ofthe third gear unit, a friction clutch for optionally connecting the sungear member and the ring gear member .of said third gear unit, and

a one way-clutch for arresting the ring gear member of said third gearunit.

3. In a transmission mechanism, in combination; a shaft; a planetarygear unit, coaxial with said shaft;,an operable clutch attached to amember of said planetarygear unit; an axially movable annular clutchmember for actuating said clutch and constituting together with said Iplanetary gear member an annular fluid/pressure working chamber, saidclutch member being actuated by a fiuid pressure in said working chamberto disengage said clutch.

4. In a transmission mechanism, in combination; a shaft; a planetarygear unit coaxial with said shaft; a fluid-pressure actuated clutchattachedto a member of said planetary gear unit;

the said shaft having a fluid-pressure channel communicating with theworking chamber of said clutch; a distributor sleeve member mounted onsaid shaft and axially movable in relation thereto and provided withopenings, optionally communicating with said fluid pressure channel insaid shaft; means for moving said distributor sleeve member in one-axialdirection; and a dis- .tributor sleeve return spring, urging saiddistributor sleeve-member in the opposite direction; a foot actuatedmember operable at will to move the distributor sleeve member oppositeto the direction of the distributor sleeve return spring force on saiddistributor sleeve member; and a foot actuated member return spring,releasing the distributor sleeve member when-the said foot actuatedmember is released.

5. In a transmission mechanism, in. combination, a shaft; a planetarygear unit, coaxial with said shaft; a fluid-pressure actuated clutchattached to amember of said planetary gear unit, there being afluid-pressure channel in said shaft, communicating with the'workingchamber of said clutch; a distributor sleeve member, movably mounted onsaid shaft and provided with openings, optionally communicating withsaid fluid-pressure channel; and a spring plunger, cooperating with saiddistributor sleeve member and said shaft and offering a limitedresistance against the motion of said distributor sleeve member inrelation'to said shaft.

6. In a transmission mechanism according to claim 5, a distributorsleeve return spring, urging the distributor sleeve member in onedirection in relation to the shaft, the force imposed on saiddistributor sleeve member by saiddistributor sleeve return spring 'beinggreater than the spring plunger resistance.

7. A transmission mechanism comprising a driving shaft; a plurality ofplanetarygear units, coaxial with said shaft; fluid pressure actuatedclutches, attached to members of said planetary gear units respectively;there being fluid pressure channels in said shaft communicating with theworking chambers of said clutches respectively; a distributor sleevemember, movably mounted on said shaft and provided with openingsoptionally communicating with the said shaft fluid-pressure channels; acentrifugal regulator rotatable with said driving shaft and comprising acentrifugal weight, a centrifugal weight return spring counteracting thecentrifugal force on said weight; means for connecting the centrifugalweight and the distributor sleeve member, said ,said distributor sleevemember and the driving shaft, the sum of the distributor sleeve returnspring force, the spring plunger resistance force and the centrifugalweight force on said distributor sleeve member, all said forces actingin the same direction, being equal to the centrifugal weight returnspring force on said distributor sleeve; a member at the lowestconvenient angular velocity of said driving shaft.

' 9. In a transmission mechanism according to claim 'I; a distributorsleeve return spring, urging the distributor sleeve member in one axialdirection; a spring plunger, cooperating with the said distributorsleevemember and the driving shaft and resisting a limited axial force'betweensaid distributorsleeve member and said driving shaft, the sumof thecentrifugal weight force and the distributor sleeve return spring forceon said distributor sleeve member, both acting in one axial direction,being equal to the sum of the centrifugal weight return spring force andthe spring plunger resistance force on said distributor sleeve member atan angular velocity or i said driving shaft, which is higher than thelowest convenient angular velocity of said.driving'shaft, multiplied bythe step up ratio between two neighboring drive ratios of thetransmission mechanism.

10. In a transmission mechanism according to claim 1; a brake optionallyarresting the ring gear member of third gear unit.

11. A transmission mechanism comprising driving and driven elements, andplanetary gear units operatively associated respectively with saidelements and with each other and jointly constituting a variable speedgearing connecting said elements, means for transmitting torque Irom thedriving element to the planetary pinion member of one coaxial planetarygear unit, the ring gear member of the said planetary gear unit beingconnected to the sun gear member of a second planetary gear unit, theplanetary pinion member of the said second planetary gear unit beingconnected to the driven element and a second planetary gear unit, theplanetary pinion member of the said second planetary gear unit beingconnected to the driven element, a friction clutch for optionallyarresting the sun gear member of the first mentioned gear unit, afriction clutch for optionally connecting the sun gear member and thering gear member of said second gear unit and a one way clutch forarresting the ring gear member of said second gear unit.

NILS ARVID PALMGREN.

